4.3. Allometry and Ontogeny
Unapparent skull asymmetries seem to be noticeable early in ontogeny in
this species, although further studies may be necessary to confirm
precisely at what point this begins. The presence of both shape and size
asymmetry in dorsal and ventral skull views is undeniable in studied
samples and more profoundly so in dorsal views (Table 1) despite similar
level of significance after multivariate regression (Table 2). Results
from the currently investigated samples (confirmed hypothesis number 2)
demonstrated a persistence of directional asymmetry throughout ontogeny,
we thus fail to accept the null hypothesis Further, skull shape changes
concentrated collectively more on rostro-dorsal and caudal areas as
growth advances, and are right side biased, (Fig. 4a and b) is
suggestive of “handedness” (a tendency to use a side of the head more
than the other naturally) in P. tricuspis. Confirmation for this
ontogenetic trajectory is consistent with Esquerre et al (2017) and does
not differ in other clades of pangolin species (Ferreira-Cardoso et al.,
2020). Literature evidence, though scarce or non-existent in this
species, suggested sex does not significantly influence shape, size
notwithstanding as a covariate in the regression model of the skull
(Ferreira-Cardoso et al., 2020). Allometric regressions of shape on size
in existing works revealed a significant overlap of intercepts inP. tricuspis with all other species and between P.
tetradactyla and P. javanicus only (Ferreira-Cardoso et al.,
2020) this position postulates both a similarity and divergence in skull
morphology of the species to provoke a cursory look at its
characterization process (Table 2; Fig. 5).
Along the first axis (Figs. 4a and b), changes involved the posthion,
nasal and maxillary regions whereas the second plane portray more shape
changes synonymous with fronto-temporal sutures and the
parieto-occipital areas, this observation was corroborated by Murphy et
al. (2001b) in placental mammals. The correlation between morphology and
modularity in the present investigation suggests that adult integration
patterns are the result of selection pressures rather than historical
constraints, and that developmental modularity played little
constraining role in diversification (Fig. 6), similar to observations
reported by Alfoldi et al. (2011) and Sanger et al. (2011) in studies
involving other arboreal species; Anolis lizards (Anolis
carolinensis ). The right and left ventro-lateral rims of the foramen
magnum presented highest portions of individual shape diversities in
ontogeny of this species as currently observed (Fig. 6), asymmetry in
architecture of this foramen easily appeared by the
5th harmonic (Tables 3 and 4) despite the
uninformative order of the angle of orientation of the EF position. Our
inferences in this regard postulate dynamic developmental outcomes
yielding foramen magnum phenotypes.